<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .demo{
            background-color: orange;
        }
    </style>
</head>
<body>
     <button id="btn">点我创建一个输入框</button>
    <script type="text/javascript">
      const btn = document.getElementById('btn')
      btn.onclick =()=>{
        const input = document.createElement('input')

        input.className = 'demo'
        input.value = 99
        input.onclick = ()=>(alert(1))

        document.body.appendChild(input)

        input.focus()
        console.log(input.parentElemnt)
      }

    </script>
</body>
</html>